Wednesday, Jun. 4, 2025

Are CO2 measurements reliable?

yes

Measurements of the amount of carbon dioxide in the atmosphere are consistent, reliable, and globally verified across multiple independent systems.

NOAA collects data from over 60 sites, including Mauna Loa, which has hosted the longest continuous CO2 record, tracking an annual increase in CO2 from 0.94 ppm in 1959 to 3.33 ppm in 2024. Mauna Loa is ideal due to its remote location and clean Pacific air, while occasional volcanic emissions are well understood and mathematically filtered out of records. In addition, hundreds of stations all over the world report to independent monitoring bodies such as the World Meteorological Organization and Europe’s Integrated Carbon Observation System.

Because CO2 mixes evenly in the atmosphere, measurements from multiple systems such as ground stations, air flasks, and orbiting instruments indicate the same story: rising CO2 levels driven by human emissions. Claims of distortion are unfounded and ignore decades of careful monitoring.

This fact brief is responsive to conversations such as this one.

Sources

NOAA Tracking carbon dioxide across the globe
NOAA How we measure background CO2 levels on Mauna Loa
NOAA What is the Global Greenhouse Gas Reference Network?
NASA How do scientists know that Mauna Loa’s volcanic emissions don’t affect the carbon dioxide data collected there?
NOAA Annual Mean Growth Rate for Mauna Loa, Hawaii
World Meteorological Organization Atmospheric CO2 monitoring continues despite Mauna Loa volcanic disruption: AEMET (Spain)

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Fact briefs are bite-sized, well-sourced explanations that offer clear "yes" or "no" answers to questions, confusions, and unsupported claims circulating online. They rely on publicly available data and documents, often from the original source. Fact briefs are written and published by Gigafact contributor publications.

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Skeptical Science is a non-profit science education organization. Our goal is to remove a roadblock to climate action by building public resilience against climate misinformation. We achieve this by publishing debunking of climate myths as well as providing resources for educators, communicators, scientists, and the general public. Skeptical Science was founded and is led by John Cook, a Senior Research Fellow with the Melbourne Centre for Behaviour Change at the University of Melbourne.

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Are CO2 measurements reliable?

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